As a soldier of the High Legions, Gnashblade first came to Lion's Arch at the age of 20 as part of an Ash Legion operation to extort the people of the city, under the banner of the Black Lion Trading Company. Gnashblade was by all accounts a dependable soldier who never disobeyed orders—until that day. When he raised concerns with his legionnaire, Aria Gnashfang, believing that attempting to intimidate the pirates of Lion's Arch would not be fruitful, the disagreement led to a fight and Gnashfang was killed. The next day, the Black Lion Trading Company was established in earnest.

In 1326 AE, during selections to appoint a new Captain's Council member, Gnashblade purchased a vessel (making him eligible) and attempted to secure a trade agreement with the Zephyr Sanctum, but narrowly lost out to Ellen Kiel.

Following the destruction of Lion's Arch, Captain Gnashblade fled to a refugee camp in the northern hills of Gendarran Fields. Under the orders of Captain Kiel, he was conscripted into the Lionguard under General Emergency Statute 14 and forced (along with all other Black Lion Trading Company merchants), to act as a deputy quartermaster for the Lionguard, upon pain of death. Since then, he has blackmailed Hero-Tron to act as his spy on the Captain's Council. Evon also has a lookalike in Lion's Arch posing as him, which explains why he has sometimes been spotted in two different locations in the city at the same time.